Light-emitting diode (LED) lamps provide a source of illumination for a variety of lighting applications, including decorative lighting, automotive lighting, architectural lighting, and other such applications. Depending on the particular application, LED chips may be packaged in a number of different ways to form the LED lamp. However, most conventional LED lamps are formed of an LED chip mounted to a lead-frame structure and encapsulated in an epoxy resin lens.
Conventional lead frames include a pair of leads, or electrodes, one to serve as the anode, the other as the cathode. An LED chip is mounted to the upper portion of the cathode, and a wire bond forms an electrical connection between the LED chip and the upper portion of the anode. When a proper voltage is applied to the electrode pair, current flows through the LED, and light is produced.
Such conventional lead frames are formed by a mechanical stamping process, with the lower portion of the leads consisting of narrow metallic strips which, when mounted in the LED lamp project perpendicularly away from the lens. Such leads may have a square or rectangular cross-section such that they form post-like structures. This type of lead frame works well when the LED lamp is to be inserted into a circuit board or connected to a panel-like support structure.
However, for those applications requiring that the LED leads be coupled to an insulated conductor, such as a decorative light string, rather than, for example, a trace on a printed circuit board, connecting the leads of conventional LED lead frames to electrical wiring poses significant challenges. In some cases, the leads may be soldered directly to ends of the conductor to form a connection. In other cases, intermediate structures, such as wire terminals, or mechanical connectors, may be used.
Commonly, wire terminals are manufactured in a stamping process separate from the stamping of the lead frames. Thus, an extra step in manufacture is often required. In such an application, the wire terminals must be separately crimped to make the required mechanical connections to the ends of the conductors. Where a wire terminal is not properly secured to a conductor, an air gap can result, thus leading to undesired electrical arcing and detrimental effects to the electrical components. Also, as briefly mentioned above, in applications where soldering is used, not only is the process more arduous, but numerous problems can arise, like cold-solder joints.
In any case dealing with LED lead frames and insulated wiring, it can be difficult to make the aforementioned electrical or mechanical connections, with the result being unreliable and inconsistent electrical and mechanical connection between the lead frame and the wiring. Such difficulties drive up the cost of manufacture and installation, and potentially decrease the safety of the lighting product.